The invention relates to a drive device for a vehicle and especially for a railroad vehicle. The invention also applies to the drive for road vehicles.
Vehicles, especially railroad vehicles, which comprise a structure mounted on at least one driving axle fitted with wheels which is driven in rotation by an electric motor, such as a radial flux motor, are known.
The motor, which is fixed to the structure of the vehicle and possibly supported by the axle via a bearing, comprises a stator and a rotor mounted so as to rotate with respect to the stator. The axle may be driven in rotation by the rotor via gearwheels constituting a gear reducer. One of the gearwheels, which is fastened to the axle, constitutes a drive element extending radially around the axle and has toothing which meshes with the pinion which may be fastened to the rotor.
In such a drive device, the motor is inserted vertically between the vehicle structure and the axle, thereby requiring the vehicle structure to be placed at a certain height above the axle. Furthermore, the use of a gear reducer has certain drawbacks, since it increases the overall size of the drive device and has difficulty in absorbing the in-service displacements between the vehicle structure and the axle.
It has been proposed to use drive devices for railroad or road vehicles comprising an electric motor placed around the axle of the vehicle, or located in the central part of a wheel.
In the case of such drive devices, the rotor may be in direct engagement with the axle or with the wheel. Direct driving of the axle or the wheel is generally performed by an internal part of the motor, generally by an internal part of the rotor.
The rotor may also constitute part of the wheel.
In all cases, only a few possibilities for movement between the axle and the drive motor remain.
In certain cases, the axle or wheel is driven via a gear reducer or a differential but, in this case, the drawbacks mentioned above in the case of railroad vehicles, whose drive device has a gear reducer, are again found.
In the work xe2x80x9cHistoire de la traction xc3xa9lectrique (History of Electric Traction)xe2x80x9d volume 1, chapter IX, pages 373-395, by Machefert Tssin et al., xc3xa9lectrique (History of Electric Traction)xe2x80x9d volume 1, chapter IX, pages 373-395, by Machefert Tssin et al., La vie du rail (Rail Life), Paris 1980, there is description of gearless transmissions providing the electric traction of a railroad vehicle, based on a motor whose armature may be mounted on a hollow shaft allowing passage and movement of an axle of the vehicle and drives at least one wheel of the vehicle via a compliant transmission.
FR-A-550836 describes a device for driving a vehicle along rails, comprising an electric motor mounted around an axle of the vehicle with the possibility of movement of the axle, the rotor of the motor being mounted on a first hollow shaft and driving the axle in rotation via the first and second hollow shafts, through which the axle passes, and via two universal joints.
It is therefore an object of the invention to provide a device for driving a vehicle comprising a structure mounted on at least one driving axle fitted with wheels, which includes at least one electric motor supported by the structure of the vehicle and having a stator and a rotor mounted so as to rotate with respect to the stator, placed around the axle but not in contact with the axle, and a drive element fastened to the axle extending radially from the axle, this device allowing the vehicle to be driven very satisfactorily, with the possibility of movement between the axle and the motor.
For this purpose, the element for driving the axle is located laterally with respect to the electric motor, along the axial direction of the axle, and the rotor is fastened to drive means designed to engage directly with the element for driving the axle in rotation.
In order to make the invention clearly understood, a drive device according to the prior art and a drive device according to the invention and according to several embodiments will now be described by way of example.